scholarly journals Influence of Grain Size Distribution on Ductile Intergranular Crack Growth Resistance

2020 ◽  
Author(s):  
Abhilash Molkeri ◽  
Ankit Srivastava ◽  
shmuel osovski ◽  
Alan Needleman
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Grain Boundary ◽  
Size Distribution ◽  
Crack Growth ◽  
Grain Size Distribution ◽  
Intergranular Crack ◽  
Crack Growth Resistance ◽  
Full Field ◽  
Finite Element Calculations

The influence of grain size distribution on ductile intergranular crack growth resistance is investigated using full-field microstructure-based finite element calculations and a simpler model based on discrete unit events and graph search. The finite element calculations are carried out for a plane strain slice with planar grains subjected to mode I small-scale yielding conditions. The finite element formulation accounts for finite deformations, and the constitutive relation models the loss of stress carrying capacity due to progressive void nucleation, growth, and coalescence. The discrete unit events are characterized by a set of finite element calculations for crack growth at a single-grain boundary junction. A directed graph of the connectivity of grain boundary junctions and the distances between them is used to create a directed graph in J-resistance space. For a specified grain boundary distribution, this enables crack growth resistance curves to be calculated for all possible crack paths. Crack growth resistance curves are calculated based on various path choice criteria and compared with the results of full-field finite element calculations of the initial boundary value problem. The effect of unimodal and bimodal grain size distributions on intergranular crack growth is considered. It is found that a significant increase in crack growth resistance is obtained if the difference in grain sizes in the bimodal grain size distribution is sufficiently large.

scholarly journals Influence of Grain Size Distribution on Ductile Intergranular Crack Growth Resistance

2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Abhilash Molkeri ◽  
Ankit Srivastava ◽  
Shmuel Osovski ◽  
Alan Needleman
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Grain Boundary ◽  
Size Distribution ◽  
Crack Growth ◽  
Grain Size Distribution ◽  
Intergranular Crack ◽  
Crack Growth Resistance ◽  
Full Field ◽  
Finite Element Calculations

Abstract The influence of grain size distribution on ductile intergranular crack growth resistance is investigated using full-field microstructure-based finite element calculations and a simpler model based on discrete unit events and graph search. The finite element calculations are carried out for a plane strain slice with planar grains subjected to mode I small-scale yielding conditions. The finite element formulation accounts for finite deformations, and the constitutive relation models the loss of stress carrying capacity due to progressive void nucleation, growth, and coalescence. The discrete unit events are characterized by a set of finite element calculations for crack growth at a single-grain boundary junction. A directed graph of the connectivity of grain boundary junctions and the distances between them is used to create a directed graph in J-resistance space. For a specified grain boundary distribution, this enables crack growth resistance curves to be calculated for all possible crack paths. Crack growth resistance curves are calculated based on various path choice criteria and compared with the results of full-field finite element calculations of the initial boundary value problem. The effect of unimodal and bimodal grain size distributions on intergranular crack growth is considered. It is found that a significant increase in crack growth resistance is obtained if the difference in grain sizes in the bimodal grain size distribution is sufficiently large.

The Influence of Microstructures on the Thermal Conductivity of Polycrystalline UO2

2016 ◽  
Author(s):  
Enze Jin ◽  
Chen Liu ◽  
Heming He
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Method ◽  
Grain Size ◽  
Finite Element ◽  
Pore Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Structural Changes ◽  
Property Changes ◽  
Design Guidance

The thermal conductivity is one of the most important properties for UO2. The influences of microstructure are especially important for UO2 due to the severe structural changes under irradiation conditions. In this study, we have investigated the thermal conductivity of UO2 with different microstructures using Finite Element Method. The thermal conductivity increases with increasing grain size. The grain size distribution has obvious influence on the thermal conductivity especially when there are pores in the polycrystal. The influences of porosity and pore size are very sensitive to the position of the pores. The results obtained in this study are useful for prediction of property changes of UO2 fuel in pile and important to gain some design guidance to tune the properties through the control of the microstructure.

Simulation of the Kinetics of Grain-Boundary Nucleated Phase Transformations

2011 ◽  
Vol 172-174 ◽  
pp. 1128-1133 ◽  
Author(s):  
Eric A. Jägle ◽  
Eric J. Mittemeijer
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Phase Transformations ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Kinetic Models ◽  
Micro Structure ◽  
Boundary Area ◽  
Random Nucleation ◽  
Kinetics Of

The kinetics of phase transformations for which nucleation occurs on parent-micro-structure grain boundaries, and the resulting microstructures, were investigated by means ofgeometric simulations. The influences of parent microstructure grain-boundary area density,parent grain-size distribution and parent→product kinetics were analysed. Additionally, thesimulated kinetics were compared with predictions from two kinetic models, namely a modelproposed for spatially random nucleation and a model proposed for grain-boundary nucleation.It was found that the simulated transformed fraction as function of time lies in between the twomodel predictions for all investigated parent microstructures and parent→product kinetics.

Improved efficiency of CdZnS thin-film solar cells

1985 ◽  
Vol 63 (6) ◽  
pp. 716-718 ◽  
Author(s):  
S. Chandrasekhar ◽  
S. Martinuzzi ◽  
F. Z. Nataren
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Solar Cells ◽  
Grain Boundary ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Ternary Compound ◽  
Thin Film Solar Cells ◽  
Base Layer ◽  
Cds Films

For low Zn concentrations i.e., x < 0.1, the performance of the Cd1−xZnxS–Cu2S solar cells can be improved by reducing the grain-boundary recombination. This has been achieved by growing well-oriented, homogeneous, ternary compound films.It was found that the Cd1−xZnxS films grown on the polycrystalline CdS films achieved the same larger grain size as that of the base layer. These films had fewer misorientations and had a unimodal grain-size distribution. There is a continuity in the crystallites from the CdS base to the Cd1−xZnxS overlayer, and the bifilms thus grown are less resistive than Cd1−xZnxS single layers.

Effect of grain size distribution on the grain boundary electrical response of 2D and 3D polycrystals

2006 ◽  
Vol 177 (35-36) ◽  
pp. 3117-3121 ◽  
Author(s):  
G DEZANNEAU ◽  
A MORATA ◽  
A TARANCON ◽  
F PEIRO ◽  
J MORANTE
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Electrical Response ◽  
2D And 3D

Grain-boundary resistivity versus grain size distribution in three-dimensional polycrystals

2006 ◽  
Vol 88 (14) ◽  
pp. 141920 ◽  
Author(s):  
G. Dezanneau ◽  
A. Morata ◽  
A. Tarancón ◽  
M. Salleras ◽  
F. Peiró ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Three Dimensional ◽  
Grain Boundary Resistivity

Effect of Grain Size Distribution on the Local Mechanical Behavior of Nanocrystalline Materials

2011 ◽  
Vol 682 ◽  
pp. 153-158
Author(s):  
Ying Guang Liu ◽  
Jian Qiu Zhou
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Boundary Diffusion ◽  
Mechanical Response ◽  
Grain Boundary Sliding ◽  
Internal Stresses ◽  
Boundary Sliding ◽  
Log Normal

A theoretical model based on self-consistent approximation is proposed to explore the effect of grain size distribution on the local mechanical response of nanocrystalline (nc) materials. The representative volume element (RVE) is composed of grains randomly distributed with a grain size distribution following a log-normal statistical function. The grain interior and grain boundary are taken as an integral object to sustain deformation mechanisms of grain-boundary sliding, grain-boundary diffusion and grain-interior plasticity. Local plastic strains and internal stresses, developing within the RVE, have been recorded and discussed.

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